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08-24-2019, 07:22 PM | #1 |
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New transmission locks up. Only spins free in neutral. Thoughts?
OK, I got the transmission assembled, double check tooth count, back lash, etc. Everything fits perfectly, but the trans locks up in forward and reverse. Only free spins when the lower/reverse slider is located in neutral (first pict on the far left).
I've read Mac VP's and Max Navarro's books. I still can't figure out the problem. The sychro hub/sleeve is very hard to move back or forward. I've placed the top on it to move the synchro fore and aft and it still locks up the trans. Any help or tips would be appreciate. Thanks. Tim Last edited by Tim Ayers; 08-25-2019 at 12:06 AM. |
08-24-2019, 07:32 PM | #2 |
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Re: New transmission locks up. Only spins free in one spot. Thoughts?
1st picture shows transmission in neutral, 2nd picture, it's in 1st gear, third picture it's in reverse gear
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08-24-2019, 07:37 PM | #3 |
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Re: New transmission locks up. Only spins free in one spot. Thoughts?
Not sure if this will help. Do you have the front bearing retainer on yet? If so, pop it off and see if it spins. I had that happen on a t87 3 speed before. I must have tightened it up cockeyed and it locked up the front bearing. The bearing retainer also has an oil groove that has to line up. Good luck, hope you figure it out.
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08-24-2019, 07:41 PM | #4 |
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Re: New transmission locks up. Only spins free in one spot. Thoughts?
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08-24-2019, 07:51 PM | #5 |
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Re: New transmission locks up. Only spins free in one spot. Thoughts?
OK, so, in neutral, if you hold the tail end of the mainshaft to prevent it spinning, can you freely turn the input shaft?
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08-24-2019, 07:54 PM | #6 | |
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Re: New transmission locks up. Only spins free in one spot. Thoughts?
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Let me take a picture of the synchros. I'm getting a hunch that may be it. |
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08-24-2019, 07:58 PM | #7 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Yes, somewhere in synchro hub, end of input shaft, or front of mainshaft, you have a problem. If you loosen the front bearing retainer, can you get true neutral?
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08-24-2019, 08:04 PM | #8 | |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Quote:
I replaced the worn synchro with one that looks a little different. It fit the same , but now I wonder. The original one had a sloped or tapered "collar". The replacement one has a block "collar". I'll swap them to see if that does it. |
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08-24-2019, 08:07 PM | #9 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
What part no's are your input shaft and 2 gears?
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08-24-2019, 08:11 PM | #10 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
I'm not sure. Would they stamped on them? I've had this set for years.
I have a complete used set that I kept together from a good known trans. I'm leaning towards cleaning up those gears, replacing the wear items and see if that works. When in neutral, aside from not allowing the input or main shafts to spins independently, the gears will spin and coast so I believe they are right. I did the gear tooth math and it worked out. It's this snychro. If I pull it out from the synchro hub, the trans works, goes into gear and main and input shaft spin free of one another in neutral. Last edited by Tim Ayers; 08-24-2019 at 08:24 PM. |
08-24-2019, 08:40 PM | #11 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
New twist. If I take out the cluster gear shaft and let the cluster drop to the bottom of the case, the trans works as it should. Hmmmm
Cluster is a NOS 28 tooth part #51A-7113A (that was in the box). |
08-24-2019, 10:18 PM | #12 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
different gear pitch, correct tooth count but wrong pitch which causes the lock up. 51A is from a later trans
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08-24-2019, 11:12 PM | #13 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
OK, thanks. According to Mac VP, it can be used. It was a later replacement for earlier gear sets.
I think I found a few issues. The brass washer between the synchro hub and second gear was too tight. I changed it for an old one I had. New one didn't leave enough slack. I have .006" now (.008" is max). Also, the sychro hub was NOS and stiff as heck. I've been working it back and forth, it has loosened up a lot. I also put the old springs in the blocks. Seems to have helped. Too late to put it back together tonight. |
08-25-2019, 12:02 AM | #14 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Now I'm completely stumped. I swapped the 28 tooth cluster out for another 28 tooth cluster that came from a 40's car.
Still locked up in all gears, but neutral and the the input and main shafts will not spin independently when in neutral. It is either the synchro hub or the synchros themselves. When the input shaft synchro is pulled away from the synchro hub, it works as it should. When mated in the hub like it should, locks up. Last edited by Tim Ayers; 08-25-2019 at 12:35 AM. |
08-25-2019, 02:59 AM | #15 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Tim How wide is the tapered synchro face at back of input shaft?
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08-25-2019, 04:27 AM | #16 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
The synchro hub and synchro rings need to be able to turn freely, as a unit, relative to the cones on the input and second gears. The synchro rings should be able to rattle around a little bit, while still be held in the right relationship to the synchro hub.
Is it all bound up? |
08-25-2019, 06:29 AM | #17 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
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08-25-2019, 06:32 AM | #18 | |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Quote:
What the heck is going on? Taking a closer look at the synchro ring (in a pict above) and the "blocks" from the old synchro assembly I had (side shift box), the blocks of had a slanted end on one side. I'm assuming this was to let the synchro spin. Not sure, just thinking out loud. All the parts I have the ones mentioned in Mac's book. I'm stepping away from it today and will come back to it on Monday, Last edited by Tim Ayers; 08-25-2019 at 06:51 AM. |
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08-25-2019, 07:11 AM | #19 |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
Your first two pictures of the blocker rings show a ring that is bad. It is badly worn from something rubbing against it on it's OD. The second two photos show the blocker ring as it should be, both the front and rear rings should be identical. How about a photo or two of rest of the syncro. What hub are you using 81A, 91A or 01A?? There are different blocker rings for the different syncros. as well as different outer sleeves.
Last edited by Terry,OH; 08-25-2019 at 07:27 AM. |
08-25-2019, 07:17 AM | #20 | |
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Re: New transmission locks up. Only spins free in neutral. Thoughts?
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